I just reviewed our wire prices for 14/2, 14/3 & 14/2/2.
14/3 is 25% more than 14/2. 14/2/2 is 76% more than 14/2. Based on these prices 2 runs of 14/2 will cost 13% more than a single run of 14/2/2 in materials alone. Add the additional to that and I definitely see the savings.
Curt